Can a Butterfly’s ‘Tail’ Boost Its Chances of Survival?

By: Jiahao Chen

A bird rapidly attacks a “helpless” butterfly, attacking the butterfly’s tail and wing. As the butterfly scrambles to run away, its tail suddenly tears apart from its body, letting it escape. After what could have been a deadly fight, the butterfly escaped only with a damaged tail, and scientists are about to realize what a butterfly’s tail can really do.

In the Proceedings of the Royal Society B., a new finding was published. It stated how a butterfly’s tail wasn’t just for style, but it could help the butterfly survive by distracting a bird from the weakest points, but rather aiming for the colorful tail.

An evolutionary biologist, Ariane Chotard, along with her group of colleagues, started researching butterfly tails after Chotard had wondered if birds would attack a butterfly’s tail. She said, “[a] lot of these butterflies display tails, and we don’t really know why.”

To start her test, she collected many Iphiclides podalirius (IF-ih-KLIH-deez Poh-dul-IR-ee-us, or sail swallowtail butterflies), in Ariege, France. The sail swallowtail gets its name from how it looks, mostly from the two black tails that extend from their wings (their tails look like the tails of the swallowtail). Above their tails, they are marked with blotches of orange and blue, which stand out from the yellow stripes that mark the rest of its body.

The finding showed that just short of half the swallowtails collected-65 out of 138-had one or more damaged tail(s). Out of those swallowtails, they looked at each wing (130 wings), and it was shown that more than 8 in 10 of those wings had a damaged tail. This finding helped create a hypothesis that predators of the butterfly tended to go attack more colorful places, sometimes completely ignoring the most vital parts!

After her test, Chotard decided to prove her hypothesis with yet another test. She captured dozens of great tits (birds), then attached real swallowtail wings to fake swallowtail bodies. She recorded the bird’s reaction to the fake swallowtails, and they vigorously attacked the fake butterflies. It was shown that the attacks were mostly focused on lower parts of the wing, and 4 out of 10 hit the blue and orange blotches and damaged the tail.

Even after these two tests, it still remains unknown if losing the tail benefits or gives a disadvantage to the butterfly. “You survived. You escaped from a predator, but maybe there’s a trade-off,” Chotard says. She then gave an example of a trade-off of losing a tail for slower agility.

The team will now try to compare the survival benefits of these tails that butterflies have. Juliette Rubin, an evolutionary biologist who works at the University of Florida in Gainesville says it would help if they could compare how butterflies with their tail would act differently against ones who have a damaged tail.